/*
 * Copyright (C) 2007 The Guava Authors
 *
 * Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except
 * in compliance with the License. You may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software distributed under the License
 * is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express
 * or implied. See the License for the specific language governing permissions and limitations under
 * the License.
 */

package com.google.common.collect;

import com.google.common.annotations.GwtCompatible;
import com.google.common.annotations.VisibleForTesting;
import java.util.Spliterator;
import java.util.Spliterators;
import javax.annotation.Nullable;

/**
 * Implementation of {@link ImmutableSet} with two or more elements.
 *
 * @author Kevin Bourrillion
 */
@GwtCompatible(serializable = true, emulated = true)
@SuppressWarnings("serial") // uses writeReplace(), not default serialization
final class RegularImmutableSet<E> extends ImmutableSet<E> {
    static final RegularImmutableSet<Object> EMPTY = new RegularImmutableSet<Object>(new Object[0], 0, null, 0);

    private final transient Object[] elements;
    // the same elements in hashed positions (plus nulls)
    @VisibleForTesting
    final transient Object[] table;
    // 'and' with an int to get a valid table index.
    private final transient int mask;
    private final transient int hashCode;

    RegularImmutableSet(Object[] elements, int hashCode, Object[] table, int mask) {
        this.elements = elements;
        this.table = table;
        this.mask = mask;
        this.hashCode = hashCode;
    }

    @Override
    public boolean contains(@Nullable Object target) {
        Object[] table = this.table;
        if (target == null || table == null) {
            return false;
        }
        for (int i = Hashing.smearedHash(target);; i++) {
            i &= mask;
            Object candidate = table[i];
            if (candidate == null) {
                return false;
            } else if (candidate.equals(target)) {
                return true;
            }
        }
    }

    @Override
    public int size() {
        return elements.length;
    }

    @Override
    public UnmodifiableIterator<E> iterator() {
        return (UnmodifiableIterator<E>) Iterators.forArray(elements);
    }

    @Override
    public Spliterator<E> spliterator() {
        return Spliterators.spliterator(elements, SPLITERATOR_CHARACTERISTICS);
    }

    @Override
    int copyIntoArray(Object[] dst, int offset) {
        System.arraycopy(elements, 0, dst, offset, elements.length);
        return offset + elements.length;
    }

    @Override
    ImmutableList<E> createAsList() {
        return (table == null) ? ImmutableList.<E>of() : new RegularImmutableAsList<E>(this, elements);
    }

    @Override
    boolean isPartialView() {
        return false;
    }

    @Override
    public int hashCode() {
        return hashCode;
    }

    @Override
    boolean isHashCodeFast() {
        return true;
    }
}
